In both switching and linear power supplies, current limiting is generally provided to prevent overcurrent and often shuts down the power supply if an overcurrent condition occurs. To this end, the high current set point is often the high point of the low frequency line frequency noise. In switching power supplies, for example, such low frequency line frequency noise is typically present when the power supply is initially energized. I have found, however, that once regulation occurs, the low frequency line frequency noise is substantially alleviated or obviated. I have discovered that it is not necessary to use the peak of the low frequency line frequency noise as the overcurrent set point once regulation occurs.
In accordance with the present invention, I have provided a regulated power supply in which the peak current including the noise is used as the overcurrent trip point before regulation, but once regulation occurs, the peak of the regulated current waveform is used as the trip point.
It is, therefore, an object of the present invention to provide a regulated power supply that is efficient in preventing overcurrent, without requiring the current set point to be always set at the high peak of the line frequency noise.
Other ojbects of the present invention will become apparent as the description proceeds.